Privacy policy

This site is published by Mostrodarte, Inc., a Delaware corporation doing business as Mostro.

A question about your data, or a request? Write to privacy@mostro.xyz.

This site sets only one cookie, mostro-etape. During the intro, it tells which step to show at the site's address (for example "jeu-2"), so the address doesn't change from one game to the next. It doesn't say who you are, is only sent with the page request to Vercel (the host, part 04), and is deleted as soon as the step opens, after a minute at most. The site has no ads, no tracking pixels, no tracking from one site to the next.

The site's fonts and scripts are served by the site itself. Your browser contacts another service only if you accept audience measurement.

Audience measurement, with Google Analytics, starts only if you click "Accept" in the banner. It counts page views and how people move around the site, so we know what works. Google's advertising signals stay off, and Google Analytics doesn't store your IP address.

If you accept, Google Analytics sets two cookies on mostro.xyz: _ga and _ga_W0HXTMPYSF. They tell one visitor from another without saying who they are, and last two years at most. If you refuse, nothing loads and neither cookie is set.

You can change your mind at any time with "Cookie settings", at the bottom of this page and in the home page menu. If you refuse after accepting, both cookies are deleted.

To work, the site stores five small settings in your browser. None of them says who you are, and none is sent anywhere.

Three stay after you close the tab:

• mostro-langue: the language you picked with the FR · EN switch, so the site's front page reopens in that language.
• mostro-intro-vue: saved when you click “Skip intro”. The site doesn't use it yet.
• mostro-consentement: your choice in the audience measurement banner ("accepte" or "refuse"), so we don't ask again.

Two are erased when you close the tab, and often sooner:

• mostro-depart: the last frame of game 3 and your stream count, so the portal starts exactly on it. Erased as soon as the portal has read it.
• mostro-arrivee: a note saying you came through the portal, so the home page follows on without a cut. Erased as soon as the home page has read it.

To clear them all: in your browser settings, delete this site's data (often under “Privacy” or “Browsing data”). The site still works afterwards; it just forgets your language and your audience measurement choice.

The site is hosted by Vercel. Like any web host, Vercel records technical data for every page requested: your IP address, your browser type, the page requested, the date and time.

These logs are used to run the site and protect it. The site itself records nothing more.

The site doesn't keep your email. When you click “Join”, it opens Mostro's Google Form in a new tab, with your email already filled in. That's all it does with it.

To fill it in, your email travels in the form's address (the link). So it can stay in your browser history and in Google's logs.

You're only signed up once you send the Google Form. If you close the tab without sending it, there is no signup.

Your answers are then kept by Mostro, in its Google Workspace, and this page applies to them. Only Mostro's founder and its marketing team can read them. The form asks for your email and whether you are an artist or a fan; you can also give the link to your social media page, say whether the Sonic Green event interests you, and sign up for the newsletter.

The beta and the newsletter are open to people aged 16 and over.

The site links to other sites: Mostro's pages on LinkedIn and X, the beta's Google Form and the Mostro app.

When you follow one of these links, you leave this site: the other site has its own rules, and your browser may tell it you came from here.

The Mostro app is a separate product: this page does not cover it.

The games' sound is made inside your browser. Nothing is recorded.

The site checks whether your screen is a touch screen and whether you asked for reduced motion, only to adapt the display. It keeps and sends none of this.

It doesn't use your microphone, your camera or your location.

Three services help us run this site:

• Google (Forms, and Workspace for our email): the beta form, its answers, and the emails you send us.
• Vercel: hosting the site, and its logs.
• Google Analytics: audience measurement, only if you accept it.

They may process data outside your country, including in the United States. Vercel covers these transfers with the European Commission's standard contractual clauses (and their UK equivalent).

This data is used for four things: running and protecting the site (the hosting logs), measuring its audience if you accepted it, handling beta signups, and writing to you if you chose to get the newsletter.

Audience measurement data is kept for 14 months in Google Analytics, then deleted.

You can ask us:

• to see the data we hold about you;
• to correct it;
• to delete it;
• to stop getting the newsletter, at any time: that withdraws your consent.
• to withdraw your consent to audience measurement, at any time, with "Cookie settings".

To do so, write to the address in part 01.

You can also complain to the data protection authority in your country.

If what the site does changes, we update this page first, and change the date below.

This page exists in French and English.

Last updated: 11 November 2026